Environmentally friendly filter cartridge

ABSTRACT

A filter cartridge which is environmentally friendly in that it is made up of components which are all incinerateable. The ends of a filter element are sealed using potting compound and plastic endcaps. The upper endcap, which is closed, has a pressure relief aperture associated therewith to prevent bowing. In a plugged filter condition the high downward pressure introduced on the upper endcap is compensated by providing the cartridge with centering ribs which bottom on an associated ledge in the housing to provide a positive stop for the top endcap, preventing it from being driven down into and through the filter element. Rubber gaskets are associated with the respective endcaps, and are reliably secured to the endcaps by being snap fit into grooves molded into the plastic of the endcaps. The lower endcap utilizes a simple radial seal gasket which is both highly effective and also positioned to avoid structural crushing forces on the cartridge. A keying system prevents the installation of improper filters.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application claims the benefit of U.S. Provisional PatentApplication No. 60/386,980 and 60/387,235, both filed on Jun. 7, 2002.

FIELD OF THE INVENTION

This invention pertains to filters, and more particularly to anenvironmentally friendly filter cartridge.

BACKGROUND OF THE INVENTION

Most conventional filters and filter cartridges present a disposalproblem. Driven by ease of installation, many applications have gone toself-contained spin-on cartridges. These have a metal outer case, ametal base plate, and other metal components within the filter.Replaceable cartridges also have significant metal components, often inthe form of centertubes or support grids for supporting the filterelement, and metal endcaps. Thus, significant elements of a filter willnot burn thus preventing the use of incineration for relatively completedisposal of the spent filters or filter cartridges.

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing, it is a general aim of the present inventionto provide an environmentally friendly filter cartridge, capable ofbeing incinerated, and which is economical to manufacture and providesfor simple and reliable installation. The cartridge is environmentallyfriendly in that it contains no metallic parts.

In practicing the invention, the cartridge can be made from a limitedclass of materials, preferably all incinerateable. The materials includethe media (normally cellulose or perhaps polyester with plasticbacking), two plastic endcaps, two rubber gaskets, and potting compound(epoxy, plastisol, hot melt or urethane), all of which areincinerateable. The cartridge itself has no centertube; to the extentinternal support is required, it is built into the housing, which iscompatible with the cartridge. The fact that the cartridge will burn andit is lightweight (due to no metal parts) simplifies disposal.

It is a feature of the invention that pre-molded plastic endcaps areutilized in the filter along with structures which compensate for thereduction in strength of plastic endcaps over conventional metalendcaps.

In a particular embodiment, the invention provides an environmentallyfriendly filter cartridge containing no metal parts. The cartridgeincludes a cylindrical filter element having an internal bore, which hasno integral supporting centertube. A pre-molded plastic endcap, havingan open center corresponding to the internal bore of the filter, it isealed to the filter element at a first end thereof. An annular grooveformed near the outer periphery of the first endcap has a radial sealgasket fitted therein. The radial seal gasket has a peripheral mountingbead sized to be stretched and snap fit into the annular groove. Theradial seal gasket has a depending skirt coaxial with the filter elementand positioned at about the outer periphery of the filter element. Asecond pre-molded plastic endcap is provided having a closed end. Thesecond end of the filter element is sealed to the second endcap. Thesecond endcap also has an annular groove at the outer periphery thereof.In this case a disc-like axial seal is stretch fit into the groove toproject from the outer periphery of the second endcap to provide anaxial seal. A pressure equalizing aperture is formed in the secondendcap for equalizing the pressure differential across the second endcapduring filter operation. Support shoulders associated with the lowerportion of the second endcap serve to resist crushing forces applied tothe second endcap during filter operation.

Subsidiary features of the invention include a handle also formed in thesecond endcap for facilitating user manipulation of the filtercartridge.

The filter cartridge, according to the invention, is used in a housing,which receives the filter cartridge. The housing has a centertube fixedtherein for supporting the inner bore of a cartridge when inserted inthe housing. A cover is threaded onto the housing in such a way as tocompress the axial seal gasket between the cover and the housing. Thepressure equalization apertures serves to equalize the pressures betweenthe upper endcap and the cover to prevent bowing of the plastic of thesecond endcap under operating pressure.

In certain applications, the upper endcap has a plurality of taperedribs positioned near the periphery thereof and oriented to assist incentering the cartridge in the housing. Shoulders formed on the taperedribs interfit with an annular ridge in the housing for supporting theshoulders to resist crushing pressures on the filters under operatingconditions.

In certain instances, the filter also has a plurality of keys associatedwith the second endcap. The key positions are on the underside of theendcap facing toward the centertube. The housing centertube has a topsurface having a plurality of keyed positions. A slot is formed in aselected one of the keyed positions to correspond with the position ofthe key on the inside of the second endcap.

Other aspects, objectives and advantages of the invention will becomemore apparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a filter constructed in accordance withthe present invention;

FIG. 2 is an elevational section taken through the filter of FIG. 1 in aplane parallel to the paper surface;

FIG. 3 is a partial enlarged view showing the upper endcap with key;

FIG. 4 is a diagram illustrating a plurality of key positions;

FIG. 5 is a partial enlarged view illustrating the lower endcap andradial seal gasket;

FIG. 6 is a partial diagram illustrating the upper endcap, with filterremoved, to better show the tapered centering guides and shoulders; and

FIG. 7 is an elevational cross-section showing a housing used with thefilter of FIG. 1.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning then to FIG. 1, there is shown, in elevation, a cartridge 20constructed in accordance with the present invention. This disclosure ofthe cartridge 20 is intended to be general, since the cartridge 20 canbe configured for different applications. More particularly thecartridge can have elements configured such that it will be used as afuel filter, a full flow oil filter, a hydraulic filter, or a bypass oilfilter. The cartridge features, which will be described in detailherein, will be common to any of the foregoing applications. Theuniversal housing, which will also be described below, is readilyreconfigureable for the foregoing applications, without the necessityfor change of the characteristics of the filter cartridge. Referringback to FIG. 1, it will be seen that the filter cartridge 20 includes afilter element 21 having a lower endcap 22, which carries a radial sealgasket 23. An upper endcap 24, also secured to the filter element 21,provides a number of features, including a mechanism for supporting anaxial seal gasket 26, an integrally molded handle 27 on the top of theendcap 24, and centering beveled projections 28, which both serve tocenter the cartridge 20 as it is inserted into the housing and whichalso have lower shoulders 29 b thereon which tend to support the plasticendcap 24 on the housing to resist crushing forces in filter operation.Also of note is a pressure equalization aperture 30 formed in the upperendcap 24, which serves to equalize the differential pressure across theendcap 24 to prevent bowing and possible fracture of the endcap 24.

The cross-sectional view of FIG. 2 reveals additional constructionaldetails of the filter of FIG. 1. There it will be seen that the lowerendcap 22, which is made of pre-molded plastic, provides an upstandingannular channel 31 into, which a first end of the filter element 21 isfit and potted. Potting can be accomplished with any conventionalpotting material used in this art, which includes epoxy, plastisol, hotmelt or urethane. The particular potting material used may depend uponthe nature of the application to which the filter is put. The pottingtends to seal the lower portions of all of the pleats into a unitaryendcap. The lower endcap 22 has a central opening 35 for passing fluidwhich is passed through the filter to the central bore thereof to ahousing outlet (not shown in FIG. 2).

The filter element 20 has an outer circumference and an open inner bore21 a. Normally flow through the filter is from the outside in, makingthe internal bore 21 a the area which receives and passes to an externalconduit the filtered fluid. It is possible, of course, to operate thefilter in the opposite direction in which the internal bore 21 a wouldbe the filter inlet, and clean filtered fluid would be obtained at theoutside periphery of the filter.

The lower endcap 22 also has an annular groove 32 formed therein nearthe periphery of the filter. The radial seal gasket 23 has an enlargedin-turned annular bead 34 which is sized to be stretched and snap fitinto the groove 32. In that way the gasket 23 is positively and reliablylocked in place on the endcap 22. The gasket 23 has a depending skirt 23a which depends from the endcap 22 and has a radius very near theoutside radius of the filter element 21, so that the axial seal performsits sealing function near the outside of the filter cartridge 20 forreasons to be explained below.

FIG. 2 also shows the upper endcap 24 which, like the endcap 22, is apre-molded plastic element. In the case of the upper endcap 24, theendcap has a closed end. An internal annular channel 36 is provided forreceiving the second end of the filter element 21. Like the first end,the second end is also potted into the associated channel in the endcap.

The upper endcap 24 has an annular groove 38 preferably located at theouter periphery thereof. A disc-like rubber annular gasket 26, whichserves as an axial seal gasket, is sized so that it can be stretched andsnap fit into the groove 38. In this way, the gasket is reliably andsecurely positioned for automatic installation with the cartridge 20.

FIG. 2 also illustrates the centering ribs 28 (see also FIG. 6 for anenlarged view). It will be seen that the ribs 28 each have an angledface 29 which, as suggested in FIG. 7, causes the filter cartridge toself center as it is slid into the housing. The housing has a circularridge 29 a (see also FIG. 7) over which the angled projections 29 rideto ultimately seat the lower shoulders 29 b on a ledge 29 c formed inthe housing. The dimensions are such that the upper endcap 24 firmlyseats the shoulders 29 b on the ledge 29 c so that additional downwardforce on the endcap 24 created by pressures during operation of thefilter will not drive the endcap 24 into the housing and crush thefilter. These ribs 28, in conjunction with the pressure relief port 30in the upper endcap 24, are significant features in allowing the use ofa plastic endcap in an application which heretofore had required thestructural stability of a metal endcap.

Also of note in FIG. 2 is the integrally molded handle 27 formed on theupper surface of the upper endcap 24. Also, as a subsidiary feature, theinside surface of the upper endcap 24 is provided with a key featuregenerally indicated at 62, which will be described in greater detailbelow.

FIG. 7 shows an exemplary housing into which the filter of FIG. 1 can befit. In the illustrated housing, inlet fluid is provided through aninlet port 42. The housing also has an outlet port 44, which isconnected by an internal passage 44 a in the housing to the center lowerportion of the filter, in fluid communication with the bore 21 a. Thehousing has a removable cap 45 which is threaded onto the housing tocompress the axial seal gasket 26 set in the annular groove 38 on theperiphery of the upper endcap 24. Also of note is the bottom 49 of thehousing, which may be removably secured in place by fasteners such asbolts. This allows the installation of different housing bottoms fordifferent applications, such as a bottom including a sump for a fuelfilter application, or a concave bottom for high pressure lubricationapplications.

The lower portion of the housing has an annular flange 46 which providesa sealing surface acted upon by the skirt 23 a of the radial seal gasket23 which, it is recalled, is carried in the groove 32 of the lowerendcap 22. The seating of the radial seal gasket 23 into the groove 32is better illustrated in the enlarged partial view of FIG. 5, while theinteraction between the radial seal 23 and the housing flange 46 is bestshown in FIG. 7. Use of a radial seal in this position is significant inthat the gasket is positioned near the outer periphery of the filter sothat the pressure differential serves to enhance the sealing action. Thegasket 23 seals radially between itself, the endcap 22 that supports it,and the housing flange 46. This seal separates the filtered andunfiltered fluid. Use of a radial seal for this component utilizes thepressure differential across the filter to assist the sealing functionby forcing the radial seal gasket 23 against both the endcap 22, whichsupports it and the housing flange 46 of the filter housing. Inaddition, placing the seal at the external periphery tends to put apressure differential across the lower endcap which is positive at theoutside of the filter (and therefore the inside of the endcap) andnegative at the bottom of the endcap. This pressure differential tendsto put the pleated paper filter in tension, which the media is capableof resisting. Moving the skirt 23 a of the gasket inboard would tend toput at least part of the media in compression, which is not so readilyresisted by pleated paper media. Keeping the media in tension isparticularly important in resisting what would otherwise be crushingforces encountered in a plugged filter condition.

Returning to the upper endcap 24, it will be seen that at least onepressure relief port 30 is formed in the upper endcap 24. The purpose ofthis port is to equalize the pressure across the upper endcap 24 toprevent bowing or possible fracture of the endcap 24. This isaccomplished by, in effect, allowing a small portion of the unfilteredfluid on the outside of the cartridge to move through the pressurerelief aperture 30 to the top of the endcap 24. The purpose is to allowthe pressure to equalize across the gasket at the top and to avoidputting undue stresses on the endcap 24 or the axial seal gasket 26.

The pressure downstream of the media is always less than the upstreampressure (when the filter is flowing fluid). This differential pressurecan be quite high in cases where the filter is plugged, the velocity ishigh, or the fluid is cold and viscous. When a pressure relief aperture30 is provided, this pressure is carried to the top of the upper endcap24 and causes an unbalanced force to be placed on the upper endcap 24,tending to force it into the housing. In practicing this aspect of theinvention, this force is counterbalanced in the housing. The unbalancedforce is due mainly to the center of the endcap 24 which has theupstream pressure on one side, and downstream pressure on the bottomside. The unbalanced force is in the downward direction and tries topush the cartridge into the housing and crush the element. The cartridgehas the aforementioned shoulders 29 b on the bottoms of the ribs 29, andthese seat against a stop 29 c to provide a positive stop for the topendcap and thus seat the overall filter in the housing.

FIGS. 3 and 4 illustrates a keying feature which can be used in thepractice of the present invention. The inside 24 a of the upper endcap24 is provided with a plurality of key positions, best illustrated inFIG. 4. It will be seen that at a given radius from the center of theendcap 24, a plurality of key positions 60 are provided. The illustratedembodiment includes eight key positions in a single ring. More or fewerkey positions per ring, as well as additional rings can also beprovided, but it is believed that the eight key positions, which canprovide the sixteen possibilities illustrated in FIG. 4, is adequate formost applications.

Referring primarily to FIG. 3, it will be seen that a single key 62 isprovided on the underside of the illustrated endcap in a given position.While only a single key is shown, as contrasted with the three keys ofFIG. 4 it is believed that the single key will adequately illustrate theinvention without overcomplicating the drawings. The key is in a fixedangular position with respect to the key circle 63 (the circle in whichthe keys are located). The key 62 projects into the internal bore 21 aof the filter element 21. FIG. 3 shows a portion of the housingcentertube 64 having a top surface 65 which is substantially solidexcept for a key opening 66. The upper surface 65 of the centertube hasa plurality of key positions in a key circle 67 in the same pattern asillustrated in FIG. 4. However, instead of projections 62, the keys inthe upper surface 65 are apertures to receive the projections. FIG. 3shows a single aperture 66 positioned in the key circle 67 to engage thesingle projection 62 positioned in the key circle 63. Thus, when thefilter is installed in the housing, the keys will align and allow thefilter to reach the seated position, allowing the cover to be placed onthe housing and operation to continue. If the wrong filter inserted, thefilter will not seat, and the user will be incapable of completingassembly.

This feature is particularly significant when using a universal housingas illustrated in this application. For example, two housings might beused side-by-side to provide a primary and a secondary fuel filtersystem. Both housings would be of the same diameter and height, butwould require different filter cartridges. The keys will prevent thecartridges for one of the housings from being installed incorrectly inthe other housing. It would be a simple matter to have several differentkey configurations to suit various applications and indeed variouscustomers.

The assembly of the filter will now be briefly described, primarily withreference to FIG. 2. Basically the endcaps 22, 24 are potted onto thefilter element 21 in whichever sequence the manufacture desires. Usingconventional techniques, an end of the filter element is placed, forexample, in the channel 31 of the lower endcap, and potting material(epoxy, plastisol, hot melt or urethane) is introduced into the channel31 to seal the ends of all the pleats and join them to the endcap 22. Asimilar operation is performed on the other end in connection withendcap 24. The gaskets 26, 23 can be preinstalled before potting, or arepreferably installed after potting by simply stretching the gaskets andsnapping them into place. The filter is then ready for packaging andready for use by the ultimate consumer. The fact that the gaskets are soreliably joined to the filter makes changing a cartridge filterconstructed in accordance with this invention about as simple aschanging a spin-on filter. The result, however, is that the spent filtercan be disposed of by incineration, rather than contributing to landfillwaste.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1-10. (canceled)
 11. An environmentally friendly filter cartridgeconstructed to fit in a filter housing, the filter cartridge comprising:a cylindrical filter element having an internal bore of a size capableof sliding over a centertube in a corresponding housing; a first endcapcoupled to a first end of the filter element, the first endcap having anopen center sized to permit the centertube to pass therethrough; and asecond endcap coupled to a second end of the filter element, the secondendcap having at least one key extending from the second endcap into theinternal bore, the at least one key sized to engage the a correspondingkey position on the centertube, wherein the at least one key engages thecorresponding key position at only one angular position of the filtercartridge relative to the centertube such that the filter cartridge canbe loaded in only one orientation.
 12. The filter cartridge as in claim11 wherein the second endcap has a plurality of keys extending from thesecond endcap into the internal bore.
 13. The filter cartridge as inclaim 12 wherein the plurality of keys are substantially identical insize.
 14. The filter cartridge as in claim 12 wherein the plurality ofkeys are positioned in a generally circular orientation.
 15. The filtercartridge as in claim 11 wherein the corresponding key position is aslot in the centertube.
 16. The filter cartridge as in claim 11 whereinthe number of keys is equivalent to the number of key positions on thecentertube.
 17. The filter cartridge as in claim 11 wherein secondendcap closes the internal bore at the second end of the filter element.18. The filter cartridge as in claim 11 further comprising a key circleextending from the second endcap into the internal bore and surroundingthe at least one key.
 19. The filter cartridge as in claim 11 whereinthe filter cartridge comprises no metal parts.
 20. The filter cartridgeas in claim 11 wherein the internal bore has no integral supportingcentertube.
 21. The filter cartridge as in claim 11 further includingthe complimentary housing for receiving the filter cartridge, thehousing having the centertube fixed therein for supporting the innerbore of the cartridge when inserted in the housing, and a cover threadedonto the housing.
 22. The filter cartridge as in claim 11 wherein the atleast one key extends in an axial direction relative to the internalbore.